Disk spiral galaxies like the Milky Way are particularly complex. The galaxy has a pronounced spheroidal component, the halo, and a flat disk. The spatial distribution of stars is not uniform, which means that they move in different ways. The shapes of the components of the galaxy and the orbits of the stars reflect the formation of the galaxy as a whole. Stars in the halo move in highly elongated orbits, then moving away from the center of the galaxy, then approaching it. The speeds of the stars reach 200-300 kilometers per second. Such speeds are common in galaxies and are associated with their large masses. The large mass allows the stars to move very quickly. Despite the fact that the speeds are high and the orbits are elongated, the galactic halo does not rotate. The orbits are chaotically oriented, and if one star rotates clockwise, then there will definitely be another that rotates counterclockwise. The total angular momentum will be close to zero.
In contrast to the galactic halo, the stars of the disk move in a flat medium, synchronously, along almost circular orbits. Their speed is also about 200-300 kilometers per second. The movement of stars in the disk of the galaxy is ordered. It can be compared to the movement of a jet of gas. The jet moves in one direction with a certain average speed, but the atoms and molecules that make up the jet deviate from the average speed. Deviations from the average velocity for stars in galactic disks are not very large – on the order of tens of kilometers per second. There are objects in the galaxy that move at much higher speeds. At its center is a supermassive black hole weighing more than four million solar masses. The stars move around the black hole in elliptical orbits at speeds of up to 5 thousand kilometers per second. Knowing the size of the orbits and velocities, we were able to calculate the mass of the black hole – the gravitating body that provides these velocities. There are many stars in the galaxy moving at high speeds. In the vicinity of the Sun (and the Sun is located at a distance of about 25 thousand light years from the galactic center), the maximum speed of stars is about 500 kilometers per second. Faster moving stars will leave the galaxy in a short astronomical time – hundreds of millions of years. Therefore, such a speed for our galaxy is the second cosmic one: it allows the star to leave the star system.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.